As I dive deeper into creating components using SPFx, I ran into yet another JSON file with invalid schema. No schema at all is better than a wrong schema!
This time the culprit is in config/serve.json. This file is used to generate the URL for debugging components, most frequently extensions. It is particularly helpful when you want to test varying properties.
Learn more from my buddy Chris Kent (Utilizing SPFx serveConfigurations) or the official docs page. (I submitted a PR to that docs page that will clean-up the parameter tables. See it in my repo: Debug SharePoint Framework solutions on modern SharePoint pages.)
So, I've updated my extension to also create an enhanced schema for the serve.json file and associate this extended schema to the file.
To use the enhanced schema from the extension, you should remove the $schema property from the file in your workspace.
The schema is in the Marketplace, and feedback encouraged in the repo.
spfx-schemas - Visual Studio Marketplace
Extension for Visual Studio Code - Generate extended schemas for SiteScript actions and gulp serve configurations